1. Field of the Invention
The present invention generally relates to the art of microelectronic integrated circuit fabrication, and more specifically to a fixture for attaching multiple lids to a multi-chip module (MCM) integrated circuit.
2. Description of the Related Art
A Multi-Chip Module (MCM), also known as a hybrid integrated circuit, includes a substrate structure on which one or more integrated microcircuit dies are mounted. The substrate structure has a multilevel architecture including alternating patterned metal conductor and dielectric layers.
The conductors layers are formed by thin film screen printing, sputtering or plating, and are patterned as lines and planes to provide power and signal interconnections between chips. Vertical interconnects (vias) are formed through the dielectric layers to appropriately interconnect adjacent conductor layers.
In order to physically and environmentally seal the dies and associated interconnections and thereby increase the durability and reliability of the MCM, the substrate structure can be formed with cavities in which the dies are mounted. After the mounting and interconnection processes have been completed, the cavities are covered with lids that are made of a ceramic material and adhered to the substrate structure using, for example, an epoxy adhesive.
The lids must be attached to the substrate structure in the proper relative positions in order to ensure that the cavities will be sealingly covered. It is possible to apply adhesive to the edge portions of the lids, and attach the lids to the substrate structure manually. However, a significant length of time is required for the adhesive to cure, and the lids can be moved out of position during subsequent handling of the MCM. If this occurs, it would be necessary to remove and subsequently attach new lids, with the accompanying danger of damaging the substrate structure.
For this reason, simple spring-loaded clamps that resemble clothespins have been used to clamp the lids to the substrate structure during the time the adhesive requires for curing. However, it is difficult in practice to accurately attach the lids to the substrate structure and then apply the clamps without moving the lids. The clamps themselves can be easily displaced, which in turn cause the lids to move out of their proper positions.